For understanding the clinical significance of sunscreen, representative photodermatoses including xeroderma pigmentosa, polymorphous light eruption, chronic actinic dermatitis and porphyria were explained. In addition, several topics concerning strategy of sunscreen use were reviewed. Finally, new strategies of sun-protection with metallothionein protein and NF-κB decoy were introduced.

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We developed an oil-based make-up remover still having a cleansing function even in a bath by utilizing polygycerol fatty acid esters, which are widely used in food industry fields. The polyglycerol fatty acid esters that have superior self-emulsification were synthesized by adjusting the molar ratio of fatty acids and polyglycerols. The phase diagrams were constructed to recognize the cleansing mechanism. In the phase diagram of a water/surfactant/oil system, W/O type microemulsion that solubilizes a small amount of water forms near the surfactant-oil axis. Regarding the washing process as proceeding from surfactant-oil axis toward water vertex in the phase diagram, it is supposed that this is the reason why the ordinary remover cannot be used in the presence of water. It was found that the amount of solubilized water could be increased by adding middle-chain alcohols as co-surfactants in the present system. By utilizing a polyglycerol ester of the middle-chain fatty acid instead of such alcohols, the amount of water dissolving in the microemulsion remarkably increased like the added alcohol system. Consequently, the make-up remover containing the polyglycerol ester of the middle-chain fatty acid could be used even in a bath, and easily removed the oil soil, dispersed in water as fine emulsion droplet.

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The color and shape of the orbital skin have specific properties, differing from those of the cheek and forehead. Changes in the properties of the orbital skin are recognized as so-called “dark circles.” To understand the variety in the color and shape of the orbital skin, we previously observed the orbital skin in 180 healthy females, and found color tone characteristics (brown, red, and blue) and various morphological characteristics. We also established a photographic scale for their scoring and reported the results of the analysis of their correlation with age at the 48th Conference of the SCCJ. In this study, to clarify the association of skin color tone with melanin and regional blood flow, analysis of skin properties by non-invasive spectroscopy and assessment by scoring using the photographic scale were performed in 60 healthy females. The brown tone score was positively correlated with the melanin index. This suggested that the brown tone in the orbital skin is due to melanin. The red tone score was positively correlated with the Hb value and negatively correlated with the blood flow rate, These results suggested that the red tone in the orbital skin is due to increased Hb and blood flow stagnation. The blue tone score was negatively correlated with oxygen saturation and blood flow, suggesting that the blue tone in the orbital skin reflects blood flow stagnation and decreased skin circulation. These results suggested the important role of regional blood flow, and changes in melanin content play important roles in changes in the color tone of the orbital skin.

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Transparency of the skin is an important factor for realizing beautiful skin, but there is only a visual sensory evaluation method by a beauty specialist. It is unclear how skin physiological characteristics can give transparency. Our purpose is to establish an objective method for evaluating the transparency of the skin and to develop a special cosmetics product which can enhance skin transparency, after investigating the mechanism of the skin characteristics which yield transparency. We developed an optical instrument that could independently measure a diffuse reflection as well as a specular reflection by assembling a polarizing filter in a gonio-spectrum photometer. We analyzed the relationship among skin transparency, specular reflection light and diffuse reflection light. It was shown that there was a strong positive correlation between the skin transparency and the intensity of the diffuse reflection light (r=0.699) and no correlation between the skin transparency and the intensity of the specular reflection light (r=0.190). The results of partial least squares (PLS) analysis of the skin transparency and the skin physiological characteristics showed that a highly transparent skin has a fine skin surface texture with a high hydration of stratum comeum, a low melanin content and a low hemoglobin content. On the basis of these results, we developed an essence that can improve skin texture and blood flow, reduce melanin content, and increase the moisture in the stratum corneum. After eight weeks' usage of this product by consumer panels (n=30), it was confirmed that the skin transparency was improved by the increase of the intensity of the diffuse reflection light by gonio-spectrum photometer measurement and by consumers' selfassessment.

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Young ladies in their 20s, as the representative age group, have a strong wish for a foundation that can provide a beautiful finish with natural skin-transparency and can allow the finish to last longer. In response to this wish, we have attempted to develop an ideal powder material that can yield the dual function described above. Based on the fundamental knowledge of the physiological and optical characteristics of human bare skin, we designed an optimal microstructure for powder with an ideal optical character. A hybrid powder, which is interference-pearl type TiO₂/mica powder covered with a fiber-type ZnO by a morphologically controlled technology, was synthesized. The powder has a dual function. As a physico-chemical function, the powder can absorb and solidify sebum with its nano-scale fiber-type ZnO (diameter: approximately 50nm) of which the microstructure is controlled at the crystalline level. As an optical character, the powder can reflect a diffuse interference red light with is generated from the microstructure of the powder surface. A foundation containing the powder (8w/w%) can maintain the initial natural finishing with a beautiful transparency and give a dryrefreshing feeling for a significant period of time through its physico-chemical ability to absorb and solidify sebum on the skin. Since this new hybrid powder provides an optical character and a useful physico-chemical character, it has proven to be a valuable cosmetic ingredient of base-makeup products.

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